System and method for a valve

ABSTRACT

Disclosed is a system including a flow regulating system. The flow regulating system may assist in ensuring a selected pressure within an inlet volume. The flow regulator may be included in a shunt assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application includes subject matter similar to PCT applications______ (Attorney Docket No. 5074X-000060-WO), ______ (Attorney DocketNo. 5074X-000062-WO), and ______ (Attorney Docket No. 5074X-000063-WO).The entire disclosure(s) of (each of) the above application(s) is (are)incorporated herein by reference.

FIELD

The subject disclosure relates to a valve, and particularly to a valveassembly having an inlet and outlet catheter.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

A subject, such as a human patient, may have a condition for which atreatment may be prescribed. For example, hydrocephalous may generallyinclude an overproduction of cerebral fluid in the ventricles of thebrain and/or an abnormal absorption or outflow of cerebral fluid fromthe brain. The condition, therefore, may cause an inappropriate orundesirable increase in volume of cerebral spinal fluid (CSF) within theventricles in the brain and an increased pressure on the brain withinthe skull.

In various instances, a shunt may be implanted into the subject. Theshunt may include an inflow catheter positioned within a ventricle ofthe brain and an outflow catheter positioned at a location remote fromthe brain. The excess cerebral spinal fluid may, therefore, flow fromthe ventricle to a selected location in the subject. The flow of the CSFfrom the ventricle through the inflow and outflow catheters may allowfor an appropriate or selected volume of CSF within the brain to achievea selected pressure on the brain within the skull. Maintaining aselected pressure within the ventricles, however, is desired.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

A catheter may be positioned in a selected portion of a subject, such aswithin a ventricle of a brain of a human subject. The catheter mayinclude passages, such as bores, through a selected portion of acatheter. The catheter may further include an internal cannula orpassage to allow flow of a selected material, such as a liquid,therethrough. In various embodiments, the catheter may allow for flow ofcerebral spinal fluid (CSF). The catheter may be implanted as a part ofa shunt system to shunt or drain CSF from a first location to a secondlocation.

The shunt assembly may include the catheter positioned within theventricle of the brain and a catheter positioned at a location remotefrom the ventricle of the brain. Positioned between the ventricle andthe remote location may be a flow regulating system. The flow regulatingsystem may include a valve assembly that is positioned in line with thecatheters. The valve assembly may be used to regulate or select apressure to be maintained within the ventricle.

In various embodiments the valve assembly may include an opening orbreaking pressure. The breaking pressure would need to be achievedand/or exceeded to open the valve and allow fluid flow through thevalve. The valve assembly may include various portions that allow forvariation of the inlet pressure prior to opening the valve, as discussedfurther herein. The valve assembly, therefore, may be used to maintain aselected volume and/or a pressure in a ventricle.

The valve assembly may include a selected opening or breaking pressure.The opening pressure may be used to select a selected pressure to bemaintained within the ventricle of the subject. Maintaining a selectedpressure within the ventricle of a subject allows for maintaining aselected volume or pressure of fluid at an inlet location of the shuntassembly. For example, the ventricle may be selected to maintain aselected volume or pressure but allowing for flow of a fluid away fromthe ventricle when an excessive or selected threshold pressure has beenreached.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is an environmental schematic view of a shunt and systempositioned in a subject, according to various embodiments;

FIG. 2 is a top plan view of a valve assembly, according to variousembodiments;

FIG. 3 is a cross-sectional view along line 3-3 of FIG. 2 ;

FIG. 4 is an exploded view of a valve assembly of FIG. 3 ;

FIG. 5A is a first perspective exploded view of a cassette assembly,according to various embodiments;

FIG. 5B is a second perspective exploded view of the cassette assemblyof FIG. 5A;

FIG. 6 is a detailed view of an interior of a cassette housing of thecassette assembly as illustrated in FIG. 5A, according to variousembodiments;

FIG. 7 is a cross-section view of an assembled cassette assembly takenalong lines 7-7 of FIG. 5A;

FIG. 8A is a first perspective exploded view of a cassette assembly,according to various embodiments;

FIG. 8B is a second perspective exploded view of the cassette assemblyof FIG. 8A;

FIG. 9 is a detailed view of an interior of a cassette housing of thecassette assembly as illustrated in FIG. 8A;

FIG. 10 is a cross-section view of an assembled cassette assembly takenalong lines 10-10 of FIG. 8A;

FIG. 11A is a first perspective exploded view of a cassette assembly,according to various embodiments;

FIG. 11B is a second perspective view of an exploded cassette assemblyof FIG. 11A;

FIG. 12 is a detailed view of an interior of a cassette housing of thecassette assembly as illustrated in FIG. 11A, according to variousembodiments;

FIG. 13 is a cross-section view of an assembled cassette assembly takenalong line 13-13 of FIG. 11A;

FIG. 14A is a first perspective exploded view of a cassette assembly,according to various embodiments;

FIG. 14B is a second perspective view of an exploded cassette assemblyof FIG. 14A;

FIG. 15 is a detailed view of an interior of a cassette housing of thecassette assembly as illustrated in FIG. 14A, according to variousembodiments;

FIG. 16 is a cross-section view of an assembled cassette assembly takenalong line 16-16 of FIG. 14A;

FIG. 17 is a schematic view of a spring having a selected free lengthand a second selected free length;

FIG. 18A is a first perspective exploded view of a cassette assembly,according to various embodiments;

FIG. 18B is a bottom perspective view of an exploded cassette assembly;

FIG. 19 is a cross-sectional view of the assembled cassette assemblytaken along line 19-19 of FIG. 18A;

FIG. 20A is a top perspective view of an exploded cassette assembly,according to various embodiments;

FIG. 20B is a bottom perspective view of an exploded cassette assembly,according to various embodiments;

FIG. 21 is a cross-sectional view of the assembled cassette assemblytaken along lines 21-21 of FIG. 20A;

FIG. 22 is a top perspective view of a valve assembly, according tovarious embodiments;

FIG. 23 is a cross-sectional view of the valve assembly of FIG. 22 takenalong line 23-23;

FIG. 24 is an exploded view of the valve assembly of FIG. 22 ;

FIG. 25 is an exploded perspective view of a cassette assembly of thevalve assembly of FIG. 24 ;

FIG. 26 is a cross-sectional view of the assembled cassette assemblytaken along line 26-26 of FIG. 25 ;

FIG. 27 is perspective view of a valve assembly, according to variousembodiments;

FIG. 28 is an exploded view of a valve and cassette assembly of FIG. 27; and

FIG. 29 is an assembled cross-sectional view of the valve assembly ofFIG. 27 , taken along lines 29-29.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

With initial reference to FIG. 1 , a shunt system 10 is illustrated. Theshunt system may include an inlet or first catheter 14 and an outlet orsecond catheter 18. The catheters, 14, 18 includes a member or wallstructure that includes or defines an exterior surface 22, 26. Thecatheters 14, 18 may include a selected length or be formed along a longor longitudinal axis. In various embodiments, the catheter 14 may beprovided as an inflow or inlet catheter or portion for the shuntassembly 10 as a hydrocephalous shunt. The hydrocephalous shunt may beconfigured, such as formed, assembled, and/or implanted to shuntcerebral spinal fluid (CSF) from a position near a first or inletportion 30 of the catheter 14 in a ventricle 34 in a brain 38 of asubject 40 to a second or distal end 42 at a position remote or awayfrom the inlet end or portion 30. The second our outlet end 38 may be ina selected portion of the subject 40, such as a peritoneum 48.

A fluid, such as a cerebral spinal fluid (CSF) may flow along thecatheter 22 from ventricle 34 generally in the direction of arrow 50toward the outlet end 38. As is generally understood by one skilled inthe art, the inlet catheter 22 may be positioned (i.e. implanted) in theventricle 34 to allow the fluid to be drained away from the ventricle34. The inlet catheter 22 may be a part of the shunt system 10 thatincludes a selected flow control system, such as a valve assembly 60,according to various embodiments, as discussed further herein.

The valve assembly 60 may be implanted in the subject 40 in anappropriate position. In various embodiments, the valve assembly 60 maybe implanted generally subdermal near an ear 64 of the subject 40, orany other appropriate location. It is understood that the inlet catheter22 may be connected to the valve assembly 60. Thus, the inlet catheter22 and the valve assembly 60 may both be implanted in the subject 40.

The subject disclosure includes an exemplary application for drainingCSF in a subject. It is understood, however, that the valve assembly 60,according to various embodiments and/or portions thereof, may be used orimplemented for alternative uses. For example, draining a selected fluidin any appropriate portion of a subject. Further, subjects may be livingor non-living. For example, the valve assembly may be used forcontrolling flow or pressure from a first tank to a second tanks ordrain.

The valve assembly 60 may be further connected to the outlet catheter26. The outlet catheter 26 may extend from the valve assembly 60 to aselected location, such as the peritoneal cavity 48 of the subject 40.The inlet catheter 22, the valve assembly 60, and the outlet catheter 26may generally be understood to be the shunt system 10, such as ahydrocephalus shunt system. The shunt system 10 may be entirelyimplanted in the subject 40.

The fluid may flow in the direction of arrow 54 through the inletcatheter 22 to the valve assembly 60. The fluid may then flow throughthe valve assembly 60 and through the outlet catheter 26 generally inthe direction of arrow 64. The fluid may then drain or pass through theoutlet catheter 26 into a peritoneal cavity 48, or any other appropriatelocation of the subject 40. It is understood that the outlet catheter 26may be positioned within the subject 40 in an appropriate location toallow for draining of the CSF from the ventricle 34 to an appropriatelocation, such as one with high blood flow. Accordingly, as illustratedin FIG. 1 , the inlet catheter 22, the valve assembly 60 and the outletcatheter 26 may be implanted or positioned in the subject 40 as a CSFshunt system.

With continuing reference to FIG. 1 and further reference to FIG. 2 ,FIG. 3 , and FIG. 4 , the valve assembly 60 is illustrated and will bedescribed in greater detail. The valve assembly 60 may include an inletend or portion 80 and an outlet end or portion 84. Each of the ends 80,84 may include connection portions to connect to the respectivecatheters 22, 26. For example, an inlet barb 88 may engage the inletcatheter 22 and an outlet barb 92 may engage the outlet catheter 26. Itis understood, however, that other appropriate connection mechanisms maybe provided to connect the valve assembly 60 to the respective catheters22, 26. Further, the first end or inlet end 80 may be connected orformed with a base member or base portion 94. The base portion 94 mayprovide a base for the valve assembly 60 and the various portionstherein, as discussed further herein. The base 94 may be formed as asingle piece with the inlet 80 and/or may be formed of separate piecesthat are fixed together, such as with selected bonding systems includingsonic welding, adhesives, and the like. Further, the base 94 may bepositioned on a sheet or cover 98. In various embodiments, the valveassembly 60 may be positioned within the subject 40, as discussed above.The sheet 98 may assist in providing a barrier between the selectedportion of the subject 40 and the valve assembly 60 and/or a firm orrigid base for the valve assembly 60. Further the sheet 98 may assist inmaintaining the valve assembly 60 in a selected position relative to thesubject 40.

The base 94 with the inlet 80 may define an inlet passage 100. The inletpassage 100 may extend to a first reservoir or directing area 104. Thedirecting area 104 may direct a flow of the fluid generally in thedirection of arrow 54 into a reservoir volume 108. The reservoir volume108 may be reached by a passage 112 between the base 94 and a dome orcover 116. The dome or cover 116 may be formed of a selected material,such as silicon and/or selected polymers, and fixed to the base 94and/or the sheet 98. The connection of the dome 116 to the base 94and/or the sheet 98 may be in any appropriate manner, again, such aswith adhesives, sonic welding, or the like. The formation of the dome116 separate from the base 94 and/or the sheet 98 may assist inmanufacturing or assembly of the valve assembly 60. One skilled in theart will, however, understand that the base 93, the sheet 98, and/or thedome 116 may be formed as a single member, according to variousembodiments. Further, the dome 116 may be formed as one member, asillustrated in FIG. 4 , and/or may be formed of a plurality of membersthat are fixed together.

The dome 116 may define, at least partially, the reservoir volume 108relative to the base 94. Further, the dome 116 may cover or encapsulatea cassette assembly 120. The cassette assembly 120 may include an inlet124 that may be reached via a passage 128 formed between the dome 116and the cassette assembly 120. The cassette assembly 120 may includevarious portions that assist in forming a selected resistance or openingpressure, as discussed further herein. The cassette assembly 120,therefore, includes the inlet 124 and a cassette outlet 132.

The cassette outlet 132 may connect or pass to a flow limiting assembly138. The flow limiting assembly 138 may also be referred to as alimiting or selective chamber assembly 138 including a chamber base 142and a chamber case or cover 146. The flow limiter assembly 138 mayinclude a chamber as included in a Delta® valve that is a valve thatminimize overdrainage of fluid, such as cerebrospinal fluid (CSF). Thechamber 142 with the case 146, therefore, assists in maintaining orlimiting a selected outflow rate from the valve assembly 60 when thevalve portion and the cassette assembly 120 is opened. For example, theflow limiting assembly 138 may limit an outflow from the valve assembly60 to a selected amount that is dependent, at least in part, on apositive pressure at the inlet side of the flow limiting assembly 138and a negative pressure at the outlet side of the flow limiting assembly138. Generally, the flow limiting assembly 138 is to maintain theselected pressure of the opening of the valve assembly to the selectedpressure, as discussed herein. The chamber 142, therefore, may includeor define a limiting volume area 150 that is reached through an inlet154 from the cassette outlet 132. The flow limiter assembly 138 mayfurther include the outlet end 84. The Delta® valve is a valve sold byMedtronic, Inc. having a place of business in Minnesota, USA.

In various embodiments the flow limiter assembly 138 may be removablyconnected to the cassette assembly 120. For example, the chamber base142 may include engaging edges or depressions 158. The engagingdepressions 158 may be engaged by wings or fingers 162 of the cassetteassembly 120. Therefore, the flow limiter assembly 138 may be removablyconnected from the cassette assembly 120, according to variousembodiments.

The valve assembly 60 may further include the cassette assembly 120 heldin the selected base or region 170 of the base 94. The cassette holdingregion 170 may include an outer wall or ridge 174 that assists inholding or fixing the cassette assembly 120 relative to the reservoirvolume 108. Thus, the valve assembly 60 may be provided as the valveassembly unit or assembly as illustrated in FIG. 2 , for implantation tothe subject 40.

Briefly, therefore, the shunt assembly 10 may include the inlet catheter22 positioned within the ventricle 34. The inlet catheter 22 will allowcerebral spinal fluid (CSF) to flow through the inlet catheter 22 to theinlet end 80 of the valve assembly 60. The CSF may flow through theinlet 80 and into the reservoir 108. Within the reservoir 108 the valveassembly 60 is substantially open to the ventricle 34. Accordingly, thepressure within the reservoir 108 may be substantially equal to thepressure within the ventricle 34.

The further passage 128, therefore, is also open to the reservoir 108.The cassette assembly 120 including a valve mechanism, as discussedherein, may open at a selected pressure that may be formed within thereservoir 108 due to the inflow from the ventricle 34 through the inletcatheter 22 of CSF or other selected fluid. At a selected pressure, thevalve mechanism within the cassette assembly 120 may open and allow anoutflow of the CSF through the cassette assembly 120 to the cassetteassembly outlet 132. The flow limiter assembly 138 may assist inmaintaining a selected outflow rate to the outlet catheter 26.Therefore, the reservoir 108 may be maintained with a selected volumeand/or pressure and to ensure that the valve assembly 60 is notsubstantially drained of CSF. In various embodiments, the reservoir maybe maintained substantially filled during use. Under various conditions,however, the reservoir 108 may not be filled and the percentage fill maybe based on the amount of production of CSF and/or drainage rate.Further, the valve assembly may be included to maintain a selectedpressure within the ventricle 34, such as about 0 centimeters (cm) ofwater to about 30 cm of water, including about 0 cm of water to about 20cm of water, and further including not more than about 20 cm of water.One skilled in the art will understand that the cm of water is measuredat standard temperature and pressure. Where the cm of water is definedin a column having a cross section area per the National Institute ofStandards and Technology.

With continuing reference to FIGS. 2-4 , and additional reference toFIGS. 5A, 5B, 6, and 7 , the cassette assembly 120, according to variousembodiments, is illustrated in greater details. The cassette assembly120 may generally include a cassette base or housing 190. The cassettehousing 190 may include an outer wall 194 that defines an internalvolume 196. Further, the wall 194 may define or form an internal thread200. The cassette assembly 120 may further include a removable orselectively positioned cap 204 that includes an external thread 208 thatmay threadably engage the internal thread 200 of the cassette base 190.Accordingly, in various embodiments, the cap 200 may threadably engagethe base 190 to assemble the cassette assembly 120. It is understoodthat other adjustable or selectively positionable connection may beprovided such as a ratchet and pawl, or other appropriate connectionmechanism. The threaded engagement may, however, allow for a selectablepositioning of the cap 204, as discussed herein. It is understood thatthe cap 204 may also be fixed to the base 190 in any appropriate manner,such as with an adhesive, sonic welding, or the like, such as when thecap 204 is positioned at a selected position relative to the base 190.Thus, the cassette assembly 120 may be assembled in any appropriatemanner. Generally the cap 204 defines or forms the inlet 124 of thecassette assembly 120.

The cassette body 190 may enclose at least a portion of a valvemechanism 220 of the valve assembly 60. The valve mechanism 220 mayinclude a ball or movable seal portion 224 that may engage a sealportion or region 228 of the cap 204. As illustrated in FIG. 7 , the cap204 may define a cone or truncated cone that includes a tapered wall232. The tapered wall or conical portion 232 may have a first diameteror dimension 236 that is greater than a diameter dimension 238 of theball 224. The tapered wall 232 may include a second dimension 242 at aseal position that is less than the dimension 238 of the ball 224.Accordingly, when the ball 224 is pressed into the seal region 228, theball 224 may seal the seal 228 by engaging the tapered wall 232. Theball 224 may be held or biased within the seal region 228 generally inthe direction of arrow 246 by a biasing member 250. The biasing membermay be a regulating member, as discussed herein, and may include aspring that may be referend to as a regulating or a biasing spring 250.The spring 250 may generally include a selected spring force that may beselected based upon a dimension of the cassette assembly 120 to ensure aselected force (e.g., a bias force) is applied to the ball 224 into theseal region 228. As discussed further herein, the seal spring 250 may bepositioned between an adjustment member 254 that may also be referred toas a rotor, which may operate as a pressure selecting member, and theball 224. The rotor 254 may assist in selecting an opening (i.e.,cracking) pressure of the cassette assembly 120 of the valve assembly60, as discussed further herein. The opening or cracking pressure may bea threshold pressure at which the valve system, such as the valvemechanisms according to various embodiments, will open and allow a flowpast the valve inlet.

The valve mechanism 220 further includes a return spring 258 thatassists in maintaining the rotor 254 seated or positioned within thecassette housing 190. The return spring 258 may engage the cap 204 andthe rotor 254 in a return spring trough or depression 262. The returnspring 258, therefore, may selectively hold the rotor 254 within thecassette housing 190 when the cap 204 is engaged to the cassette housing190.

Further the cassette assembly 120 may include a sealing member 266 thatmay be a washer or ring. The sealing member or washer 266 may be engagedbetween the cap 204 and the cassette housing 190. For example, asillustrated in FIG. 7 , the sealing member 266 may be sealingly engagedto the cassette housing 190 when the cap 204 is engaged (e.g., with therespective threads) to the cassette housing 190. Thus, the internalvolume 196 within the cassette housing 190 may be sealed orsubstantially closed relative to an external environment save throughthe inlet 124 and the cassette outlet 132.

Briefly, with reference to FIG. 7 , at least a portion of the cassetteassembly 120 may operate as the valve mechanism for the valve assembly60. The inlet 124 is positioned within the valve assembly 60 on aninflow side or to allow inflow of fluid generally in the direction ofarrow 280. When the pressure is great enough to overcome the force ofthe spring 250, the ball 224 may also generally move in the direction ofarrow 280. The CSF may then flow through the inlet 124 and into thevolume 196. The CSF may then flow through the outlet 132 generally inthe direction of arrow 284. Thus, the CSF may enter the inlet 124 of thecassette assembly 120 and pass through the valve seal portion 228 due tomovement of the ball 224 away from the valve seal 228. The CSF may flowthrough the cassette volume 196 and generally in the direction of arrow284 out the cassette outlet 132.

The cassette assembly 120 may be set or assembled to include a selectedopening pressure due to the positioning of the spring 250 and a springforce or opening force created by the spring 250 placed on the ball 224in the seal 228. The force applied by the spring 250 against the ball224 may be selected due to the position of a regulating base or surface290 of the adjustment member 254 relative to the sealing region 228. Asillustrated in FIG. 7 , the sealing region 228 may seal against the ball224 when the ball 224 is at a selected position. For example, the ball224 may have a seal contacting edge or surface 294 that engages thesealing region 228. The position of the sealing edge 294 of the ball 224may be selectively positioned at different heights relative to thespring engaging surface 290 of the rotor 254 to alter or change theforce applied by the spring 250 to the ball 224.

With continuing reference to FIG. 5A and particular reference to FIG.5B-7 , the cassette assembly includes a selecting region 300. Theselecting region 300 can include two or more surfaces (also referred toas steps) that have height variations within the cassette volume 196. Afirst height may be defined by a base or bottom floor surface 304. Asecond height may be defined by a first step or raised region 308. Athird height may be defined by a second step 312. Similarly a fourth andfifth height may be relatively defined by respective steps 316 and 318.As illustrated in FIG. 6 , the first step 308 may have a height 322relative to the base or floor 304. The second step 312 may have a secondheight 326 relative to the base 304. Each of these steps or positions304-318 may include different or varying height and the illustration ofthe two heights 322, 326 is merely for the clarity of the currentdiscussion. In various embodiments, for example the step height may varyby about 0.001 millimeters (mm) to about 0.5 mm, including about 0.01 mmto about 0.3 mm, and further including about 0.1 mm to about 0.2 mm.

The rotor 254 may include an adjusting region 330. The bottom region 330may include a foot or step engaging portion or surface 334. The stepengaging portion 334 may extend a distance 338 from a bottom surface 342of the rotor 254. The distance 338 may allow the foot or step engagingportion 334 to selectively and separately engaged one or more of theregions 304-318 of the height selecting region 300.

Further, the rotor 254 may include a central bore or passage 346. Thebore 346 may include a selected shape, such as a polygon shape that mayinclude a substantially pentagon shape, including a plurality of sides,such as a side 350. The cassette housing 190 may define or include acentral peg or projection 354. The projection 354 may include aplurality of sides and generally have a selected cross-section or outershape, such as a polygon shape that may include a pentagon shape. Theprojection 354, for example, may include a plurality of sides 356.Accordingly, the projection 354 may be engaged in the passage 346 of therotor. As the projection 356 and the passage 346 are complementary inshape, the rotor 254 may be rotated to selected positions relative tothe projection 356 and then rotationally held relative thereto due tothe non-circular shape of the projection 354 engaging the recess orthrough bore 346. Thus, the rotor 254 may be rotationally positioned andheld on the projection 356.

When the rotor 254 is rotationally positioned on the projection 356, thefoot or positioning portion 334 engages one of the selected step orsurface portions of the selecting region 300. For example, at a firstposition, the foot 334 may engage or contact the surface of the base304. At a second position, the foot 334 may engage the first step 308and be positioned the height 322 above the base 304.

As the foot 334 engages the step 308, the foot 334 is the distance 322above the base 304. Accordingly, the distance 322 causes the rotor 254to compress the spring 250 when the seal member 224 is positioned in theseal or seat 228. The compression of the spring 250 would applyadditional force, due to the height 322, to the ball 224 into thesealing region 228. The biasing force, therefore, would be increased oraltered relative to when the rotor 254 is positioned in the rotationalposition such that the foot 334 engages the base 304. Similarly, as therotor 254 is rotated on to one of the other steps of the selectingregion 300, the force or initial bias applied to the spring 250, andrespectively, to the ball 224 would be altered.

The position of the rotor 254 on a selected one of the steps at theselecting region 300 selects an initial or opening force applied to movethe ball 224 away from the sealing region 228. Accordingly, bypositioning the rotor 254 to have the foot 334 engage a selected one ofthe steps or portions 304-318, the opening force required to move theball 224 generally in the direction of the arrow 280 is altered suchthat the greater the height away from the base 304, the greater theforce required to move the ball 224 out of the sealing position to theseal 228. Each of the steps may be selected to achieve a selectedopening pressure such as about 0 cm of water to about 40 cm of water,including about 0 cm of water to about 20 cm of water, and include apressure greater than about 20 cm of water.

Further, the cap 224 that is threadably engaged to the cassette housing190 may also have a position of the cap 224 altered relative to therotor 254. The cap 204 for example, may be loosened or moved generallyin the direction of arrow 246 to decrease an opening pressure and/ormove generally in the direction of arrow 280 to increase an openingpressure. A thread pitch of the threads 200, 208 may be selected toallow adjustments less than the adjustment caused by moving the rotor254 to a different one of the steps in the adjustment region 300.Therefore, fine tuning or adjustments between the steps of theadjustment region 300 may be achieved by moving the cap, such asthreading or unthreading the cap 204, relative to the rotor 254 in thealternative directions 246, 280.

Accordingly, the cassette assembly 120 may be set to a selected openingpressure, such as during manufacturing or at any appropriate time. Forexample, the valve mechanism 220 may be assembled into the cassettehousing 190 at a selected opening pressure. The same valve mechanism maybe set to a different opening pressure by positioning the rotor 254 at adifferent position on the adjustment region 300. Therefore, the valvemechanism 220 may be used to achieve a plurality of fixed or selectedvalve opening pressures with the same valve mechanism parts.

Additionally, or alternatively, a user may select a pressure at orduring implantation from one of the plurality of possible openingpressures. The cassette assembly 120, may thereafter include theselected opening pressure without need for adjustment and/or ability tobe adjusted after implantation without removal of the cassette assembly120.

In various embodiments, the regulating spring 280 may be fixed to therotor 254 in a selected manner such as with welding, adhesives, or thelike. Similarly, the return spring 258 may also be fixed to the rotor254 in a similar manner. It is understood, however, that the compressiveforces of the cap 204 against the rotor 254 may selectively hold therespective springs 250, 258 in place during the use and operation of thecassette assembly 120.

Additionally, the rotor 254 may include a plurality of the step engagingportions 334 depending upon the configuration of the adjustment assembly300. Further, in addition to and/or alternatively to the return spring258, the rotor 254 may be bonded to the cassette housing 190 in aselected manner. For example, the rotor 254 may be adhered to theadjustment portion 300 with a selected adhesive that is biocompatible tohold the rotor 254 in a selected position relative to the cassettehousing 190. The return spring 258 may be provided or not provided suchthat the rotor 254 is held in the cassette housing 190 without thereturn spring 258.

Further, the rotor 254 may include any selected passage shape that maybe complementary to the projection 354 in the cassette housing 190. Forexample, the projection 354 may be hexagonal, octagonal, or any otherappropriate shape. The shape may determine the number of selectedadjustments at which the rotor 254 may be positioned relative to thecassette housing 190 and may also depend upon the number of variationsprovided in the adjustment region 300. Accordingly, the illustration ofa pentagon shape of the projection 354 is merely exemplary and, forexample, a hexagon shape may be provided along with six optional stepsin the adjustment region 300.

With continuing reference to FIGS. 1-4 and additional reference to FIG.8A, 8B, 9, and 10 , a cassette assembly 420 is illustrated. The cassetteassembly 420 may be included with the valve assembly 60, as discussedabove. The cassette assembly 420 may include portions similar to thecassette assembly 120, as discussed above. Accordingly, portions thatare substantially identical to the cassette assembly 120, as discussedabove, will not be discussed in greater detail here but may be discussedwith reference to the cassette assembly 120. The cassette assembly 420may include portions substantially identical to the cassette assembly120, such as an outlet 132, an engagement or connection wings orprojections 162. The cassette assembly 420, therefore, may be connectedto or within the valve assembly 60. The cassette assembly 420, however,may include a valve mechanism 430 that may be positioned within thecassette housing 434 to selectively adjust or select an opening pressurein a manner as discussed further herein.

The cassette housing 434 may include an outer wall 438 that defines aninternal thread 442, similar to that as discussed above. Accordingly, acap 446 may also include an external thread 450 that may threadablyengage the internal thread 442. The cap 446 may also include or definean inlet 454 similar to the inlet 124 as discussed above. Therefore, thecassette assembly 420 may be positioned in the valve assembly 60 in asimilar manner as the cassette assembly 120, as discussed above.

Further, the cap 446 may define a seal region 460 that seals against orengages a sealing member, such as a ball 464. The ball 464 may be biasedinto the sealing region 460 with a biasing member 468, which may be apressure regulating spring, similar to the spring 250 as discussedabove. The valve mechanism 430 may further include an adjustment member472, which may also be referred to as a rotor 472. The adjustment member472 may selectively provide a selectable or selected position of theregulating spring 468 within the cassette housing 434. As discussedfurther herein, the rotor 472 may be positioned within the cassettehousing 434 to assist in selecting an opening pressure of the cassetteassembly 420. Further, a return spring 476 may be provided to assist inholding the rotor 472 within the cassette housing 434. As discussedabove, however, the rotor 472 may also be fixed within the cassettehousing 434, such as with an adhesive or similar mechanism. Further, thevalve assembly 430 may include a sealing member 480, such as a washer orO-ring.

As discussed above, the sealing member 464 may be a sphere or ball andmay be positioned within the sealing region 460 of the cap 446. Theregulating spring 468 may bias the ball 464 against the sealing region460. An upper regulating surface 490 of the rotor 472 that contacts orengages the spring 468 may be moved within the cassette housing 434 to aselected height such that the regulating surface 490 is positioned aselected height from the sealing position 494 of the ball 464 within theseal 460.

The rotor 472 may have a bottom or second surface 500 that is opposed oropposite the spring engaging surface 490. The rotor 472 may furtherinclude one or more projections, such as a first outer projection 504and a second inner projection 508. The two projections 504, 508 mayproject a selected distance 512, 516 from the bottom surface 500. Invarious embodiments the distances 510, 516 may be identical. In variousembodiments, however, the distances 512, 516 may be different.

The projections 504, 508 engage a selecting mechanism or area 520 withinthe cassette housing 434. The selection area 520 may be similar to theselection area 300, as discussed above. The selection area 520, however,will be discussed further herein. It is understood, however, that theselected area 300 may include various portions of the selection area 520and vice versa.

The selection area 520 may include an outer or first set of selectionregions 528. As discussed above, the selection region 528 may include alowest or floor position 532 and a plurality of steps each raised aselected distance relative to each other and the base or floor 532.Accordingly, the outer steps or selection region 528 may include thebase or floor 532 and four steps of varying heights or upper surfaceshaving distance of varying distance relative to the base 532. The stepsor selection regions 532-540 allow for positioning the rotor 472 atvarious heights relative to the cap or the sealing region 494 similar tothe alternative distances discussed above.

The selection area 520 may further include an inner selection area 560.The inner selection area 560 may also include a plurality of selectionregions 564, 568, 572, 576, and 580. The individual inner selectionportions 564-580 of the inner selection area 560 may also differ inheight from one another similar to the outer selection area 520.

The outer selection area 520 may cooperate with the outer projection 504and the inner selection area 560 may cooperated with the inner selectionprojection 508 of the rotor 472. Therefore, the rotor 472 may engagewith the two projections 504, 508 two different selection areas 520,560, respectively. This may allow for the rotor 472 to be rotationallyfixed relative to the housing 434 in a manner greater than the singleprojection 334 of the rotor 254 engaging the single selection ring orportion 300 of the cassette 120 discussed above.

Further, the rotor 472 may be defined or formed with a closed surfaceand not include a passage to engage a projection of the cassette housing434. In addition to the selection areas 520, 560, the cassette housing434 may further include a rotational engagement or fixation region 600.The rotational fixation region 600 may also be referred to a rotor guideor indicator guide to engage an indicator or radial projection 604 ofthe rotor 472. The radial projection or indicator 604 may radiallyextend from an outer wall 608 of the rotor 472. The indicator 604 may bereceived or engage a passage or slot 612 defined between two inwardlyprojecting walls or projections 616, 618. The inwardly projecting walls616, 618 may project a selected distance from an internal surface 622 ofthe cassette housing 434. Accordingly, the indicator guide or slot 612may engage the indicator 604 to rotationally hold or assist inrotationally holding the rotor 472 relative to the cassette housing 434.In this way, the rotor 472 may be rotationally fixed or held within thecassette housing 434 with a plurality of mechanisms including the heightselection portions 520, 560, engaging the respective projections 504,508 of the rotor 472 and the indicator 604 be engaged in one of aplurality of slots 612 of the indicator guide portion 600. Accordingly,it is understood that the indicator guide 600 may include a plurality ofthe slots 612 that may aligned with the indicator 604 at each of thedifferent selection regions of the selection portions 520, 560.

The cassette assembly 420 including the rotor 472 may selectively biasthe sealing ball or member 464 into the sealing region 494. As exemplaryillustrated, the outer projection 520 may include a selected height 630relative to the base or lowest portion 532. The inner region 560 mayinclude a similar or equivalent height. Accordingly, the inner and outerprojections 508, 504, respectively, may respectively engage a selectedone of the regions of the selection regions 520, 560 to position thespring engaging surface 490 at a selected distance from the sealingregion 494 of the sealing portion 460. As discussed above by varying thedistance of the surface 490 relative to the sealing region 494 alters acompression, and therefore the biasing force, of the spring. Thus, theforce required to move the ball 464 away from the sealing area 460generally in the direction of arrow 650 may be altered or selected.

As discussed above, the selection regions 520, 560 may be used to adjustthe rotor 472 relative to the sealed position 494 in the seal 460. Inaddition and/or alternatively thereto, the cap 446 may be rotatedthrough the interaction of the external threads 450 and the internalthreads 442 to move the cap 446 either in the direction of the arrow 650and/or in the direction of arrow 654 to adjust the force applied to theseal member 464. As discussed above, the thread pitch of the threads450, 442 may be selected to allow for an adjustment of a position of theseal position 494 relative to the rotor 472 that is less than the heightof the respective steps in the selection regions 520, 560, similar tothat discussed above in the cassette assembly 120. Therefore, thecassette assembly 420 may also be used to select an opening pressure ofthe valve mechanism 430 within the cassette assembly 420, similar to theselection within the cassette assembly 120, as discussed above, but withthe additions of variations as discussed above.

Turning reference to FIGS. 11A, 11B, 12, and 13 , a cassette assembly720 is illustrated and will be described further herein. The cassetteassembly 720 may include various portions similar to those as discussedabove, and details of the similar or identical portions will not berepeated in detail herein, however, reference to the prior discussionmay be made. Accordingly, it is understood that various portions of thecassette assembly 720 may be similar or exchanged with the portions asdescribed above and may be used in addition and/or alternatively theretoand vice versa.

The cassette assembly 720 may include a cassette housing 724, similar tothe cassette housing as discussed above, such as the cassette housing190 of the cassette assembly 120. The cassette housing 720 may includean external or outer wall 728 and may define an internal thread 732,again similar to that as discussed above. The cassette assembly 720 mayfurther include a cap 736 which may define or include an external thread740. Formed through the cap 736 may be an inlet 744 similar to the inlet124 of the cassette assembly 120. Accordingly, the cassette assembly 720may include the cap member 736 that may be engaged to the cassettehousing 724 and define an internal volume or portion 748. The cassetteassembly 720, such as in the cassette housing 724, may further includethe outlet 132 and the connection portions 162. Thus, the cassetteassembly 720 may include portions similar to those as discussed above,and including various portions as further discussed herein.

The cassette assembly 720 may further include a valve mechanism 760. Thevalve mechanism 760 may include various portions, similar to those asdiscussed above. A rotor 764 may be included in the valve mechanism 760that includes a spring seat surface 768 that may engage a biasingmember, such as a regulating spring 772. The regulating spring 772 mayengage or be placed on the surface 768 and further against a valve orsealing member, such as a valve ball 776. The valve sealing member 776may engage a seal portion or region 780 defined by the cap 736, similarto the seal regions as discussed above. The ball 776 may include anouter dimension that engages the seal region 780 in a sealed or closedconfiguration at a seal position 784. As discussed above, the regulatingspring 772 may bias the sealing ball 776 against the sealing surface780, generally in the direction of arrow 790.

The valve mechanism 760 may further include a return spring 794 that maybe engaged by the cap 736 to assist in holding the rotor 764 in aselected position within the cassette housing 724. Further a seal member798, such as a washer or O-ring may be positioned between the cap 736and the cassette housing 724 to assist in maintaining or creating a sealbetween the cap 736 and the cassette housing 724 to seal orsubstantially close the internal volume 748 within the cassette assembly720.

The cassette assembly 720 includes the rotor 764. As illustrated inFIGS. 11A and 11B, the rotor 764 may have a non-curved or circular outeredge. The rotor 764 may include an outer edge or geometry that may be apolygon that includes one or more facets, such as a plurality ofsubstantially straight or planar edges 790. In various embodiments, therotor 764 may include five edges, 790, 794, 798, 802, 806. Each of theedges 790-806 may engage an internal wall surface of the cassettehousing 724. For example, as illustrated in FIG. 12 , the cassettehousing 724 may include a complementary number of walls 810, 814, 818,822, 826. Accordingly, the cassette housing 734 may substantially definea pentagon depression or internal shape that may be complementary to anouter pentagon shape of the rotor 764. The complementary non-circularshapes may assist in holding the rotor 764 at a selected rotationalposition within the cassette housing 724.

As discussed above, the cassette housing may further include an openpressure selection portion, such as one or more selection areas. Forexample, the cassette housing 724 may include an outer selection area830 and an inner selection area region 834. It is understood, however,that only a single one of the selection areas may be provided and two ismerely exemplary. Similarly, as discussed above, the outer selectionarea 830 may include a selected number of portions that have differingheights that may vary the position of the rotor axially or relative tothe seal position 784. In various embodiments, for example, fivepositions may be formed including a first position 840, a secondposition 844, a third position 846, a fourth position 848, and a fifthposition 850. Similarly the inner selection region 834 may include fiveselection positions such as a first inner selection position 860, asecond position 864, a third position 868, a fourth position 872, and afifth position 876. Each of the respective positions of the outerselected region 830 and the inner selected region 834 may engage orcontact a respective outer foot or projection 900 or an inner foot orprojection 904. As discussed above, the projections 900, 904 may extenda selected distance from a bottom surface 910 that may be opposed oropposite the spring engaging surface 768.

Further, similar to the selection regions as discussed above, each ofthe individual steps of the respective outer selection regions 830 andthe inner selection region 834 may differ in height relative to a baseportion. For example, as illustrated in FIG. 12 , the first portion 840may be a base or floor of the cassette housing 724 and the first step844 may include a selected height or distance 914 above or away from thesurface 840 of the first portion 840. Each of the other portions orsteps may include a selected distance from the previous or otherselected steps and may, therefore, engage the respective projections900, 904 at different or varying heights relative to the seal regions784.

As discussed above, therefore, the rotor 764 may be rotationallypositioned within the cassette housing 724 to vary the position of thespring engaging surface 768 relative to the bottom surface of thecassette housing 724 and the sealed position 784 of the seal region 780.As the rotor 764 is selectively positioned, the spring engaging surface768 may be generally moved in the direction of the arrow 790 to decreasethe spring distance of the regulating spring 772. As the spring distanceis decreased (i.e., the spring is compressed) the biasing force appliedto the seal ball 776 may be increased and, therefore, a greater pressureis required to open the valve mechanism 760 by the flow of materialgenerally in the direction of arrow 920 into the inlet 744.

Further, the rotor 764 may include an indicator or a projection 930. Theindicator or projection may be positioned in one or more recesses 934 oralignment depressions 934 that are formed between each of the wallsurfaces 810, 814, 818, 822, 836. While the cassette housing 724 isunderstood to include a plurality of the recesses 934, only a single oneis discussed here for clarity of the current discussion. The recessesmay be provided to further rotationally fix the rotor 764 within thecassette housing 724. Accordingly, once the rotor 764 is selectivelypositioned within the rotor in a selected rotational position, theindicator 764 may be received within the recess 934 to assist in fixingthe indicator 764 within the housing 724.

Further, markings may be provided within the cassette housing 724 toassist in identifying the result in opening pressure based upon thepositioning of the rotor. For example, an indicator arrow or marking 940may point or be directed to a selected one of the recesses 934. Further,a marking or indication 944 may be provided to provide a specificindication of an opening pressure that would be achieved or selected onthe indicator 930 is positioned in the recess 934 indicated by the arrow940. Accordingly, during assembly a user may understand the selectedposition or opening pressure when the rotor 764 is positioned within thecassette housing 724 in a selected position. The selected position mayselect or define a threshold or opening pressure of the valve mechanism760, similar to that as discussed above.

Further, as discussed above, a final calibration may occur due to arotation of the cap 736 within the cassette housing 724. As discussedabove, the interaction of the internal threads 732 with the externalthreads 740 may allow for fine adjustments of the opening pressurebetween the steps due to a position of the rotor 764 within the cassettehousing 724.

The rotor 764 may be held in a selected position axially, such asgenerally in the direction of the arrows 790, 920 with the return spring794 or other appropriate mechanism. As discussed above, the rotor 764may also be and/or alternatively be bonded or fixed within the cassettehousing 724. In various embodiments, for example, a solvent may beapplied to either the rotor 764 and/or the cassette housing 724 to bondthe tube in a selected position. This solvent may then be evaporate andallow for a permanent bond of the rotor 764 within the cassette housing724. Further, the positioning of the rotor 764 relative to the cassettehousing 724 may be performed at a selected time, such as during amanufacturing, immediately prior or during an implantation procedure, oranother appropriate time.

Turning reference to FIGS. 14A, 14B, 15, and 16 , a cassette assembly1020 is illustrated. The cassette assembly 1020 may include portionssimilar to that as discussed above, such as the cassette assembly 120.Accordingly, similar or identical portions will not be described indetail, however, variations or additional and/or alternative portionswill be described in detail.

Generally the cassette assembly 1020 may include a cassette housing 1024that includes an outer wall portion or body 1026. The outer wall portion1026 may define an internal thread 1028 and also an internal volume1030. The internal volume 1030 may include a volume of CSF, as discussedabove. Further, the cassette housing may include the connection portion162 and the outlet 132.

The cassette assembly 1020 may include a cap 1040 that defines an inlet1044, similar to the inlet as discussed above. Accordingly the cassettehousing 1024 may be filled with a selected material through the inlet1044 through the cap 1040. Further the cap 1040 includes an externalthread 1048 that may engage the internal thread 1028 of the cassettehousing 1024. Therefore, the cap 1040 may be thoroughly engaged to thecassette housing 1024.

In various embodiments, the thread connection of the outer threads 1048and the inner threads 1028 may form a seal to seal the volume 1030. Invarious embodiments the threaded engagement of the threads 1028, 1048may form a convoluted or torturous seal. In various embodiments,however, for example including those discussed above and/oralternatively thereto, a seal member 1052 may be provided to assist insealing or substantially closing the volume 1030 when the cap 1040 isplaced on the cassette housing 1024. According to various embodiments,however, including those discussed above and further herein, the sealmember 1052 may not be necessary or required given the interaction ofthe external threads 1048 with the internal threads 1028 and/or asealing material positioned at the interaction of the threads.

The cassette assembly 1020 further includes a valve mechanism 1060. Thevalve mechanism 1060 may include an adjustment member that may also bereferred to as a rotor 1064 that includes or defines a spring engagingor regulator engaging surface 1068. The spring engaging surface 1068 mayengage or hold a biasing member, which may be a regulating spring 1072,relative to the cap 1040. The spring 1072 may engage or hold a sealingmember 1076, such as a ball seal, relative to the cap 1040 that definesor forms a sealed region 1080. The seal region 1080 defines a sealposition 1084, similar to that as discussed above. Accordingly, thepressure regulating spring 1072 may hold the sealing member or ball 1076relative to the seal region 1080 with a biasing or a spring force untilan inlet pressure, generally in the direction of arrow 1088, overcomesthe force applied by the spring 1072 to allow inflow of fluid ormaterial into the cassette housing 1024 such as within the volume 1030.

The amount of force required to move the sealing member 1076 out of theseal position 1084 (i.e., the threshold pressure) may be adjusted byaltering the force applied by the regulating spring 1072 such as byselecting a compression of the spring 1072. The cassette housing 1024may include or define an internal adjustment or selection area includingone or more adjustment areas, similar to those discussed above. Invarious embodiments, the cassette housing 1024 may define an outeradjustment area 1090 and an inner adjustment area 1094. The outeradjustment area 1090 may include a selected number of steps or variableheights relative to a or from a first adjustment position 1098 through aselected number of other steps or positions, such as four otherpositions for a total of five positions, including 1100, 1104, 1108, and1112. Similar to the adjustment areas discussed above, for example, adifference in height may be present from the first region 1098 to thesecond region 1100. The height difference may be a height or a distance1116. The height 1116 may move the rotor surface 1068 closer to the sealregion 1084 and decrease the height that the spring 1072 and, therefore,increase the spring force applied to the seal ball 1076. Accordingly,similar to the discussion above, positioning of the rotor further awayor closer to the seal position 1084 may alter the force required to openthe seal ball 1076 from the seal position 1084 and the seal 1080.

The adjustment region in the cassette assembly 1024 may also include thesecond adjustment region 1094. The second adjustment region may alsoinclude a selected number of adjustment positions, such as fiveadjustment positions 1130, 1134, 1138, 1142, and 1146. Each of these mayagain be positioned at different heights equivalent to the heights ofthe first adjustment position or portion 1090.

The adjustment positions 1090, 1094 may be engaged or contacted by oneor more projections from the rotor 1064. The rotor 1064 may include afirst projection 1150 which may be an outer projection and a secondprojection 1154 which may also be referred to as an inner projection.Each of the projections 1150, 1154 extend a distance 1158 from a surface1162. The surface 1162 is generally opposed to the surface 1068 thatcontacts the spring 1072. Accordingly, as the projections 1150, 1154, orany appropriate number of projections, contacts one or more of theselected portions of the one or more adjustment regions 1090, 1094. Therotor 1064 may be moved closer to or further away from the seal position1084 and, therefore, adjust or select a pressure applied by theregulating spring 1072 to the sealing member 1076. Nevertheless, due tothe regulating spring 1072 the sealing member or ball 1076 may move outthe seal 1080 to allow an inflow of fluid.

The rotor 1064 may be fixed within the cassette housing 1024 in aselected manner, including those discussed above such as with aretaining spring, bonding, or other appropriate connection. In variousembodiments, either in addition to or alternative to the above-discussedholding systems, the rotor 1064 may be snap fitted to the cassettehousing 1024.

The rotor 1064 may include a selected shape, such as a polygon shapeincluding a selected number of sides, as exemplary illustrated includingfive sides 1180, 1184, 1186, 1188, and 1190. The rotor 1064, therefore,may be substantially pentagon in shape. It is understood, however, thatthe rotor 1064 may be formed in any appropriate shape such as anyappropriate polygon shape including a selected number of sides. Therotor housing may include a complementary number of walls to engage orinteract with the rotor 1064 to hold a rotor 1064 in a selectedrotational position. In various embodiments, for example, a first wall1200 and a second wall 1204 may engage two of the edges or walls of therotor 1064. It is understood that the rotor housing 1024 may include anynumber of walls to engage the rotor 1064 and the discussion of the twowalls 1200, 1204 is merely exemplary. In various embodiments, forexample, five walls may be provided to interact with the five edges ofthe rotor 1064. Between the respective walls may be a recess ordepression 1206 that may interact with an indicator 1210. The indicatormay be engaged in the recess 1206, similar to the indicator 930, asdiscussed above. Further markings may be provided, such as an indicationmarking 1214 to provide an indication of a selected pressure or positionof the rotor 1064 within the housing 1024.

One or more of the walls 1200, 1204 or any of the other walls mayinclude one or more slots or ridges. For example, the wall 1200 mayinclude a first slot 1220 and a second wall 1204 may include a secondslot 1224. The edges, such as the edge 1184 may be received in the slot1224 and the edge 1186 may be received in the slot 1220. Therefore, theindicator 1210 may be held within the recess 1206. Thus, the rotor 1064may be snap fit into the cassette housing 1024.

In various embodiments, for example, the rotor 1064 may be formed of amaterial that may resiliently deform during insertion into the cassettehousing 1024. Selected materials may include thermos-plastics likepolypropylene, Acetal, polysulfone or polyethersulfone, combinationstherefore and/or copolymers thereof. During insertion, the edges 1184,11186 may deflect and then move into the slots 1220, 1224 when the rotoris moved into the housing 1020.

Further, additional tools or mechanisms may be used to assist in holdingthe rotor 1064 during insertion. For example, an assembly tool 1240 maycontact or engage tool engaging holes or depressions, such as a firsthole 1230 and a second hole 1234 of the rotor 1064. The tool 1240 mayinclude a first tip 1244 and a second tip 1246 that engage therespective holes or depressions 1230, 1234 to allow for a press fit orforce generally in the direction of arrow 1250 to press the rotor 1064into the cassette housing 1024. The indicator 1210 may be aligned withone or more of the depressions, such as the depression 1206 and the tool1240 may be engaged in the holes 1230, 1234 to press the rotor 1064 intothe housing. The edges may resiliently deform and then snap or relaxinto the respective slots, such as the slot 1220 and the slot 1224. Therotor 1064 may thereafter be rotationally and axially held within thecassette housing 1024. Thus, the rotor 1064 engaging the selectedadjustment regions 1090 and/or 1094 may define a position relative tothe sealed position 1084 to generate a spring force or a biasing forceagainst the seal member 1076.

Again, as discussed above, the rotor, according to various embodimentsincluding the rotor 1064, may be fixed within the cassette housing 1024to select a fixed and selected opening pressure that moves the seal ball1076 generally in the direction of arrow 1088. Thus the rotor 1064 maybe snap fit into the slots, as discussed above.

Further, the cap 1040 including the outer thread 1048 may be movedrelative to the inner thread 1028 to adjust a force applied to the sealball 1076. As discussed above, the threaded interaction may allow for afine turning due to movement of the cap 1040 generally in the directionof arrow 1088 and/or the direction of arrow 1260. The movement of thecap 1040 relative to the rotor 1064 may fine tune or adjust to thepressure on the ball 1076 and the force applied by the regulating spring1072 in adjustments finer than the adjustments of the adjustment regions1090, 1094 due to the distances, such as the distance 1116.

Turning reference to FIG. 17 , as discussed above, a regulating biasingmember 1280 may be provided in a valve mechanism, according to variousembodiments, including the regulating spring or biasing member asdiscussed above. In various embodiments, as discussed above, a rotor orother mechanism may be used to adjust an amount of compression, such asthrough a height or spring force applied by the biasing member relativeto a seal or seal position. According to various embodiments, inaddition to the rotor and/or alternatively thereto, the biasing member1280 may have its length adjusted. For example, as illustrated in FIG.17 , the biasing member 1280 may include a first height 1284 and/or asecond height 1288. The second height 1288 be greater than the firstheight 1284 of the biasing member 1280. Due to the greater height orfree length of the biasing member 1280 the force applied by the biasingmember 1280 relative to a sealing position relative to any fixed baseposition or distance from the sealing position may be increased.Accordingly, the opening or cracking force of the seal mechanism may beincreased by only increasing the free length or height, such as thelength 1288 relative to the first length 1284.

In various embodiments, a single spring or biasing member may beprovided for installation into a plurality of different valvemechanisms, such as the valve mechanism 60. An opening or cracking forcemay be selected or achieved by lengthening or stretching the biasingmember 1280, such as a regulator spring, to one of a plurality ofselected links. In various embodiments, for example, the first length1284 may include a first or provide a first opening pressure of a valvemechanism. Whereas stretching the biasing member to the second length1288 may include a different or achieve a different or second openingpressure. Accordingly, in various embodiments, the opening pressure oropening force required to open the valve mechanism may be adjusted orachieved by selecting or forming the spring or biasing member 1280 aselected length. Achieving the selected length may include stretching orcompressing the spring after the spring is formed.

While adjusting the biasing or spring member 1280 may be provided inaddition to and/or alternatively to the use of a rotor to achieve aselected force on the sealing member, as discussed above. In variousembodiments, however, the use of adjustment of the spring member 1280may alone and/or substantially alone be used to adjust or select anopening force applied or required to open a valve member.

According to various embodiments, with continuing reference to FIG. 17and additional reference to FIGS. 18A, 18B, and 19 , a cassette assembly1320 is illustrated. The cassette assembly 1320 may include portionssimilar to those discussed above, such as in the cassette assembly 120.The cassette assembly 1320, therefore, may include a cassette housing1324 that includes an outer wall 1328 the outer wall 1328 may define orform an internal thread 1332. Further, a cap 1336 may include or form anouter or external thread 1342. The external thread 1342 may threadablyengage the internal thread 1332. The interaction of the cap 1336 withthe housing 1324 may form or define a cassette volume 1346. Further, asdiscussed above, the threaded interconnection of the external threads1342 in the internal threads 1332 may form a seal to seal or define thevolume 1346. In various embodiments, however, an additional seal member,such as an O-ring or seal 1350 may be provided between the cap 1336 andthe cassette housing 1324 to assistant sealing the cap 1336 to thehousing 1324.

Further, the cassette assembly 1320 may include or define a sealmechanism 1356. The seal mechanism 356 may include or be defined by orformed by the regulating spring 1280. As discussed above, the regulatingspring 1280 may be stretched or provided at a selected height, such asthe height 1284 and/or the height 1288. The sealing mechanism 1356 mayfurther include a sealing member, such as a sealing ball 1360. Thesealing ball 1360 may engage a seal 1364 that may be a conical ortruncated conical portion. The seal 1364 may be a truncated cone.Further, the seal member 1360 may have a seal position 1366 similar tothat discussed above. Accordingly, the height of the biasing member 1280may be stretched to select a force applied to the sealing member 1360between a spring contacting surface 1370 of the cap 1336 and the sealposition 1366.

As illustrated in FIGS. 18A to 19 , the biasing member 1280 may directlycontact the cap 1336, such as at the surface 1370. Accordingly, theopening force of moving the sealing member 1360 from the sealed position1366 may be provided by the height of the biasing member 1280 whencontacting the cap 1336. The cassette housing 1324, according to variousembodiments (including those discussed above), may define an inlet 1374that allows for inlet of a fluid generally in the direction of arrow1378. The biasing member 1280 may hold the sealing member 1360 againstthe seal 1364 until a force overcomes the biasing force of the springmember 1280. Nevertheless, as discussed above, the cassette assembly1320 need not include an additional rotor or adjustment mechanism.According to various embodiments, the rotor may be used in addition toand/or alternatively to selecting a height of the biasing or springmember 1280, according to various embodiments.

Further the threaded engagement of the external threads 1342 and theinternal threads 1332 may also operate to move the surface 1370generally in the direction of arrow 1378 away from the sealing position1366 or in the direction of arrow 1380 toward the sealing position 1366.Thus, by threading or unthreading the cap 1336, a further adjustment, asdiscussed above, to the force applied to the sealing member 1360 may bemade.

Further, as illustrated in FIGS. 18A to 19 , the inlet 1374 may beformed through the cassette housing 1324 rather than the cap 1336. Theseal 1364 may also be formed at the cassette housing 1324 rather than atthe cap 1336. Thus, according to various embodiments, the inlet may bepositioned relative to the seal member 1360, according to variousembodiments, in any appropriate position.

The biasing member 1280 may further be fixed to the cap 1336 at thesurface 1370 in an appropriate manner. For example, the biasing member1280 may be adhered to the cap 1336, such as with an adhesive or otherbonding material or system. In various embodiments, for example, thebiasing member 1280 may be bonded to the cap 1336 by providing a solventthat dissolves a selected portion of the cap 1336 and the spring 1280 isthere by bonded to the cap 1336.

With continuing reference to FIG. 17 and additional reference to FIGS.20A, 20B, and 21 , a cassette assembly 1420 is illustrated. The cassetteassembly 1420 may include portions similar or identical to thosediscussed above, and those portions will not be discussed in greaterdetail here. Accordingly, the cassette assembly 1420 may be included inthe valve assembly 60, in addition to and/or alternatively to thecassette assemblies as discussed above. The cassette assembly 1420 mayinclude a cassette assembly housing 1424 that includes an outer wall1428 that defines an internal thread 1432. Further, the cassette housing1424 may include the connection 132 and the connection 162. The cassetteassembly 1420 may include a cap or top 1434 that defines or forms aninlet 1438. The cap 1430 may define an external thread 1442. Theexternal thread 1442 may threadably engage the internal thread 1332 ofthe cassette assembly housing 1424.

The interaction of the cap 1434 with the cassette assembly housing 1424may form or define a volume 1446. As discussed above, according tovarious embodiments, the thread interaction of the threads of 1432, 1442may seal the volume 1446 at least through the cap edges 1434. In variousembodiments, however, an additional sealing member 1450 may also beprovided between the cap 1434 and the housing 1424. Thus, the flow offluid through the cassette assembly 1420 may be through the inlet 1438and the outlet 132.

Further, the cassette assembly 1420 may include a valve mechanism 1454.The valve mechanism 1454 may include the biasing member 1280, asdiscussed above. The biasing member 1280 may form a biasing forceagainst a sealing member 1458 by selecting or forming a length or freelength of the biasing member 1280.

The valve mechanism 1454 includes the sealing member 1458 which may beheld or engaged in a seal 1462. The sealing member 1458 may be sealed ata seal position 1466 within the seal 1462. The length or height of thebiasing member 1280 may achieve or form the sealing force are closingforce of the seal member 1458 into the seal 1462. The seal 1462 may, asdiscussed above, be formed as a cone or truncated cone, such that thesealing member 1458 may be pressed into the seal 1462 with theregulating or biasing member 1280.

Is illustrated in FIGS. 20A to 21 , the biasing member 1280 may be fixedor held it to a spring engaging surface 1470 within the housing 1424.Accordingly, as discussed above, the biasing member 1280 may alone orsubstantially alone be used to achieve a selected cracking or openingforce of the sealing member 1458 from the seal 1462. As discussed above,a rotor may be used to adjust the position of the biasing member 1280relative to the seal position 1466, however, such a router is notrequired according to various embodiments.

The biasing member 1280 may be bonded to the engaging surface 1470 in anappropriate manner, including those as discussed above. The biasingmember 1280 may be adjusted to a selected free height, such as theheight 1284 and/or the high 1288 to achieve a selected opening force toallow flow of a material through the inlet 1438 generally the directionof arrow 1474. Thus, the cassette assembly 1420 need not include arotor, but may alternatively include one as discussed above. The openingforce may be further adjusted or tuned by the threaded engagement of thecap 1434 with the cassette housing 1424. As discussed above movement ofthe cap 1434 by the threaded engagement or interaction may move the cap1434 generally in the direction of arrow 1474 and/or in the direction ofthe arrow 1478 to adjust or select a pressure applied to the sealingmember 1458 in the cassette assembly 1420.

Accordingly, the cassette assembly, according to various embodiments,may be provided in the valve assembly 60 as discussed above. Further,various cassette assemblies may include various features that may beinterchanged or used alternatively with one another, as also discussedabove. The rotor may or may not be provided to achieve a selectedopening pressure, as long as the opening pressure may be selected suchas by adjusting the length of the spring alone or biasing member alone.The rotor, however, may be provided to allow for selection, such asefficient selection, or a particular opening pressure. The particularselection may allow for similar or multiple pieces to be used to formvale assemblies of several selected and/or different opening pressures.Other mechanisms, such as the threaded cap adjustment and/or the freelength of the spring adjustment may allow for fine tuning and/or fineropening pressure selections or adjustments.

The number of projections of the rotor to interact with a selectionregion, as discussed above, may be provided in an appropriate manner toselect or maintain a selected height or position of the rotor within thevarious cassette housings. In addition, the rotor may be provided in anappropriate geometry to interact with the cassette housing to achieve arotational and/or axial position to maintain the selected position ofthe rotor to maintain a selected pressure or height of the biasingmember, also referred to as a regulating spring or member, within thecassette assembly.

In various embodiments, as discussed above, the valve assembly 60 mayinclude the inlet 80 and the outlet 84. The inlet 80 and the outlet 84may be generally aligned and/or coaxial along an axis A (FIG. 2 ). Invarious embodiments, the cassette assembly, such as the cassetteassembly 120 may include the valve mechanism or cassette inlet 124generally along or having a central axis B and the outlet 132 may extendalong an axis C. The axis B may not be aligned with the axis C. Invarious embodiments, as illustrated above, axis B may be substantiallyorthogonal to axis C. Thus, at least one of the inlet or the outlet ofthe cassette assembly, according to various embodiments, may not bealigned with the axis A.

As discussed above the valve assembly 60 may be provided in the shuntassembly 10 to assist in providing a selected flow rate and/or pressurewithin the ventricle of the subject. In various embodiments, the valveassembly 60 may include the cassette, according to various embodimentsas discussed above such as the cassette 120. In various embodiments,however, the valve assembly 60 may include additional and/or alternativecassette assemblies. For example, as illustrated in FIGS. 22, 23, 24,25, and 26 a valve assembly 1560 is illustrated. The valve assembly 1516may include various portions that are similar or identical to thosediscussed above which will be discussed only briefly here. Briefly, andwith returning reference to FIGS. 1-4 , the valve assembly 1560 mayinclude an inlet 1564, a passage 1568, a reservoir 1572 a flow-limitingchamber assembly 1576 including a chamber cover 1580 and a chamber flowcontrol 1584 and an outlet 1588. The valve assembly 1560 may further bepositioned on a sheet or cover 1592. Accordingly, the valve assembly1560 may include various portions that are similar to those discussedabove, such as in the valve assembly 60.

The valve assembly 1560, however, may include a cassette assembly 1620positioned within the cover or dome 1574. The cassette assembly 1620 maybe similar in various features to the cassette assemblies as discussedabove, such as the cassette assembly 120. The cassette assembly 1620may, however, generally be elongated as illustrated in FIG. 24 . Thecassette assembly 1620 may include the outlet 132 in the connectionportions 162 to interconnect with the flow limiting portion 1584 withinthe cover 1580. Further the cassette assembly 1620 may be held within acassette receiving portion 1624 of a base 1626 of the valve assembly1560. The cassette receiving section 1624 may be formed to receive aportion of the cassette assembly 1620, such as an inlet or first side orportion 1628.

With continuing reference to FIGS. 22-24 , and particular reference toFIGS. 25 and 26 , the cassette assembly 1620 is discussed andillustrated in greater detail. The cassette assembly 1620 may generallyextend along an axis 1629 and have portions aligned relative thereto, asdiscussed herein. The cassette assembly 1620 may include a cap 1640which may include an inlet or define an inlet 1644. The inlet 1644 mayallow a flow of a fluid generally in the direction of arrow 1646 intothe cassette assembly 1620 along the axis 1629. The inlet 1644 may bepositioned near or assist in defining a seal or seat 1650.

A sealing member, such as a ball 1654, may be positioned or biased intothe seal or seat 1615 with a biasing member 1658. The ball 1654 may sealat a seal position 1662 in the seal 1655 positioning the ball member1654 within the seal 1650. The biasing member 1658 may generally biasthe ball 1654 generally in the direction of an arrow 1666 into the seal1650 at the seal position 1662. The biasing member 1658 may bepositioned between an outlet member 1670 that defines or forms a biasingmember contacting surface 1674 to contact the biasing member 1658.

The outlet member 1670 may further define an external thread 1678 thatmay threadably engage an internal thread 1682. The cap 1640 may berotatably moved relative to the outlet member 1670 to move the cap 1640in the direction of either arrow 1646 and/or the arrow 1666. Themovement of the cap 1640 relative to the outlet member 1670 mayselectively compress the biasing member 1658 to achieve or select a freeheight and/or spring force or biasing force applied by the biasingmember 1658 against the sealing member 1654 and to the seal 1650.Accordingly, a position of the cap 1640 relative to the outlet member1673 may select an opening pressure force to move the seal member 1654away from the seal position 1662.

As discussed above, the cassette assembly, such as the cassette assembly120, may be used to select an opening or cracking pressure of the valvemechanism 1560. A valve mechanism 1680 of the cassette assembly 1620 mayinclude the seal portion 1650, the seal member 1654, and the biasingmember 1658. Thus, rotating the cap 1640 relative to the outlet member1670 may axially position the cap 1640 relative to the outlet member1670 and select a biasing force applied to the seal member 1654. Thebiasing force may select or achieve a selected opening force to selectan opening pressure or cracking pressure (i.e., threshold pressure) forthe sealing member 1654 relative to the cassette assembly 1620 of thevalve assembly 1560. A separate rotor, therefore, may not be required toselect the cracking pressure.

The cassette assembly 1620 may further include a seal member 1684, suchas an O-ring. The seal member 1684 may be positioned between the cap1640 and the outlet member 1670 to seal a cassette volume 1688 withinthe cassette assembly 1620. The cassette volume 1688 may be definedbetween the cap 1640 in outlet member 1670 and may be accessed throughthe inlet 1644 when the seal end 1640 moves away from the seal position1662.

Once the cracking pressure is selected and achieved (such as bypositioning the cap 1640 relative to the outlet member 1670), the cap1640 may be fixed relative to the outlet member 1670 in an appropriatemanner. As discussed above, various mechanisms may be used to fix thecap assembly or member 1640 to the outlet member 1670 such as adhesives,sonic welding, bonding or the like. In various embodiments, the capmember 1640 may be bonded to the outlet member 1670 in a selectedposition. Once fixed, therefore, the cassette assembly 1620 may be fixedat the selected position and at the biasing force to achieve a selectedinlet pressure of the cassette assembly 1620. The cassette assembly 1620may then be assembled into the valve assembly 1560, as discussed aboveand further into the shunt assembly 10.

The valve assembly 1560, as discussed above, may have the cover 1574.The cover may have a maximum external dimension 1690 that is generallyless than about 1 millimeter (mm) to about 5 mm less than a minimumexternal dimension 1690 of the valve assembly 1560 between the positionof the maximum dimension and the outlet 1588. Thus, during a possiblerevisions, the valve assembly 1560, according to various embodiments,may be removed through a single incision.

Turning reference to FIGS. 27, 28, and 29 , a valve assembly 1760 isillustrated. The valve assembly 1760 may include portions similar tothose discussed above, such as in the valve assembly 60. The valveassembly 1760 may include various additional and/or alternative portionsas discussed further herein. For example, the valve assembly 1760 mayinclude an inlet 1764 and a flow limiting chamber assembly 1768. Theflow limiting chamber assembly 1768 may include an outlet 1772 and aflow limiting chamber portion 1776 and a chamber cover 1780. The valveassembly 1760 may further include a reservoir volume 1780 that isdefined or formed by a cover 1784. The cover 1784 may include a materialsimilar to the cover of the dome of the valve assembly 60 as discussedabove. Further, the valve assembly 1760 may include an inlet member 1786into the flow limiting chamber assembly 1768. The inlet 1786 maygenerally allow a flow of a fluid such as the CSF generally thedirection of an arrow 1790. Further, the inlet 1764 may allow a flow ofthe fluid generally in the direction of arrow 1794. The valve assembly1760 may further include a cassette assembly 1820. The cassette assembly1820 may include an inlet 1824 and an outlet member 1826 that forms ordefines an outlet 1828. The outlet 1828 and the inlet 1776 may becovered or connected by a connection member 1832. Further, the cassetteassembly 1820 may be held or covered by the cover 1784. Thus, the valveassembly 1760 may be substantially in line or elongated valve assembly.The valve assembly 1716 may include portions that are similar to that asdiscussed above, such as the valve assembly 60. Further, the valveassembly 1760 may include portions that are replaced or alternative toand/or in addition to the valve assembly 60 as discussed above.Nevertheless, the valve assembly 1760 may be included in the shuntassembly as discussed above, and further herein.

The valve 1760 including the cassette assembly 1820 may include portionssimilar to those to the cassette assemblies discussed above, such as thecassette assembly 120. The cassette assembly 1820 may define or includea valve mechanism that includes a cap 1824 that may define or form aninternal thread 1826. The internal thread 1826 may engage in externalthread 1830 of an outlet and/or member 1834. The cap 1824 may threadablyengage the outlet member 1834 with the thread 1830 to move the cap 1824generally in the direction of arrow 1838 and/or the direction of 1842.The cassette assembly 1820 may further include a sealing portion ormember, such as a ball member 1846. Further, the cassette assembly 1820may include a biasing member 1850. The biasing member 1850 may hold orbias the sealing member 1846 against a seal or seat 1854 at a sealposition 1858. The seal position 1858 may be the position that the ball1846 seals the cassette assembly 1820, such as a cassette volume 1860.Again, the threaded connection may close the cassette a selected amountand/or a seal member 1863, such as an o-ring, may also be included inthe cassette assembly 1820.

The seal member 1846 may be moved away from the seal position 1858 by aforce of a fluid, such the CSF, moving generally in the direction ofarrow 1842. As discussed above, for example, the cap member 1824 may bemoved relative to the outlet member 1834 to select a compression forceor length of the biasing member 1850. The biasing member 1850,therefore, may apply a force to the sealing member 1846 to seal thecassette assembly 1820. The position of the cap 1824 relative to theoutlet member 1834 with the biasing number 1850 therein may be used toachieve or select an opening or cracking force required to move the sealmember 1846 away from the seal position 1858 and allow flow of a fluid,such as the CSF, generally in the direction of arrow 1842 and out to theoutlet 1772.

As discussed above, once the selected cracking or opening force iscreated or achieved, the cap 1824 may be bonded to the outlet member1834. Bonding of the cap 1824 to the outlet member 1834 may be similarto that as discussed above. The cap 1824 may be fixed to the outletmember 1834 with an intensive, sonic welding, a solvent bonding, or thelike. Nevertheless the cassette assembly 1820 may be used to achieve orselect a cracking or opening pressure within the valve assembly 1760.

The valve assembly 1760 may include a maximum external dimension 1890that is greater than about 5 mm than a minimum external dimension 1894.The valve assembly 1760, therefore, may be a “V” shape. The valveassembly may further or alternatively include a third external dimension1898 that is similar, such as less than 2 mm different, than the maximumexternal dimension 1890. The valve assembly 1760, therefore, may be afigure “8” or dumbbell shape. The valve assembly 1760 may, therefore,include a small dimension and selected external volume such as forpositioning in a small area or subject.

In various embodiments, as discussed above, the valve assembly 60 mayinclude the inlet 1564 and the outlet 1588. The inlet 1564 and theoutlet 1588 may be generally aligned and/or coaxial along an axis C(FIG. 23 ). In various embodiments, the cassette assembly, such as thecassette assembly 1620 may include the valve mechanism or cassette inlet1644 generally along or having a central axis E and the outlet 132 mayextend along an axis F. The axis E may be aligned with the axis F. Thus,all of the axes D, E, and F may be substantially aligned. In variousembodiments, the axes D, E, and F, may be generally aligned along theaxis 1629.

As discussed above, the shunt assembly 10 may include the valve assembly60 or a valve assembly according to various embodiments as discussedherein. The valve assembly may include various features or portionsincluding all of those discussed herein, all those alternatively oradditionally provided with one another, or according to variousembodiments of a cassette assembly as discussed herein. Therefore, thevarious embodiments discussed herein are not necessarily mutuallyexclusive, unless so indicated above. Thus the shunt assembly 10 may beprovided in the subject to achieve a selected opening pressure or have aselected opening or cracking pressure to allow or select a flow of CSFfrom the ventricle of the subject. The various valve assemblies may beused to achieve a selected fixed opening pressure once selected duringmanufacture and/or prior to implementation. In various embodiments, asdiscussed above, the valve assemblies including the selected cassetteassemblies may be used to select an opening or cracking pressure withinthe valve assembly for the shunt assembly to achieve a selected resultand/or treatment for the subject.

As also discussed herein, the biasing member according to variousembodiments may be a coil spring, a leaf spring, a compliant ordeformable member. Thus, the biasing member may be provided andimplemented to provide a selected biasing force on a seal member into aseal portion or seat. The seal member may also include a sphere, curvedsurface member, conical member or other appropriate shaped member thatmay seal and unseal from a seal or seat.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. A shunt system configured to be placed in asubject, comprising: an inlet having an inlet connection portion and abore therethrough; an outlet having an outlet connection portion and abore therethrough; a reservoir in a fluid flow path from the inlet tothe outlet, wherein a fluid is operable to flow into the inlet, throughthe reservoir, and out the outlet; a valve mechanism positioned betweenthe inlet and the outlet to control a flow from the inlet to the outletat a selected threshold pressure, wherein the valve mechanism comprises,a first adjustment member having a valve seal portion and a firstthread; a second adjustment member having a bias member seat and asecond thread; a seal member configured to seal the shunt system whenpositioned at the valve seal in a seal position; a biasing memberconfigured to bias the seal member against the valve seal portion with aselected biasing force, wherein the biasing force is selected at leastin part by the position of the first adjustment member relative to thesecond adjustment member; wherein the first thread of the firstadjustment member threadably engages the second thread of the secondadjustment member and to select a dimension between the seal positionand the bias member seat.
 2. The shunt system of claim 1, wherein thefirst adjustment member is formed as a single piece having a cylindricalouter wall.
 3. The shunt system of claim 1, wherein the valve sealportion includes an internal wall formed as a truncated cone. 4 . Theshunt system of claim 1, wherein the seal member is spherical and anouter surface of the seal member engages the valve seal portion at theseal position to seal the valve mechanism.
 5. The shunt system of claim1, wherein the valve mechanism includes an external maximum dimensionthat is less than at least one of a minimum external dimension of thereservoir.
 6. The shunt system of claim 1, wherein the biasing member isa spring; wherein the biasing force is selected based upon a compressionof the spring between the seal member and the bias member seat.
 7. Theshunt assembly of claim 1, wherein the inlet and the outlet aregenerally aligned along a single axis and the valve seal member isconfigured to move along the axis to between an open position and asealed position.
 8. The shunt of claim 1, further comprising: a flowlimiter assembly having a flow limiter and a cover; wherein the flowlimiter limits a flow rate from the reservoir.
 9. The shunt system ofclaim 8, wherein the flow limiter limits flow due to a siphon effectfrom an outlet catheter.
 10. The shunt system of claim 8, wherein thevalve mechanism further comprises: a valve mechanism outlet configuredto connect to a flow limiter inlet; and a projection extending near thevalve mechanism outlet to engage a recess of the flow limiter assemblyto operationally connect the valve mechanism and the flow limiterassembly.
 11. The shunt system of claim 1, further comprising: at leastone of an inlet catheter connected to the inlet or an outlet catheterconnected to the outlet.
 12. The shunt system of claim 8, furthercomprising: a cover configured to cover at least the valve mechanism andat least partially define the reservoir with a base member; wherein thecover includes a cover maximum external dimension that is greater than aflow limiter assembly maximum external dimension.
 13. A method offorming a shunt system configured to be placed in a subject, comprising:providing an inlet connection portion with a bore therethrough;providing an outlet connection portion and a bore therethrough; forminga reservoir between a cover and a base in a fluid flow path between theinlet connection and the outlet connection; providing a valve mechanismpositioned between the inlet and the outlet to control a flow from theinlet to the outlet at a selected threshold pressure, comprising, firstadjustment member having a valve seal portion and a first thread to asecond adjustment member having a bias member seat and a second thread;positioning a seal member configured to seal the shunt system whenpositioned at the valve seal in a seal position within the firstadjustment mechanism of the second adjustment mechanism; biasing theseal member with a biasing member configured to bias the seal memberagainst the valve seal portion with a selected biasing force, andpositioning the first adjustment member relative to the secondadjustment member to achieve a biasing force with the biasing memberagainst the seal member.
 14. The method of claim 13, wherein connectingthe first adjustment member to the second adjustment member includesthreadably connecting the first adjustment member to the secondadjustment member to achieve a selected dimension between the sealposition and the bias member seat.
 15. The method of claim 14, furthercomprising: positioning the seal position at one of a plurality ofdimensions from the bias member seat.
 16. The method of claim 15,further comprising: selecting the selected biasing force; and creatingthe selected biasing force by positioning the seal position at one ofthe plurality of dimensions from the bias member seat.
 17. A shuntsystem configured to be placed in a subject, comprising: an inlet havingan inlet connection portion and a bore therethrough; an outlet having anoutlet connection portion and a bore therethrough; a reservoir in afluid flow path from the inlet to the outlet, wherein a fluid isoperable to flow into the inlet, through the reservoir, and out theoutlet; a valve mechanism positioned between the inlet and the outlet tocontrol a flow from the inlet to the outlet at a selected thresholdpressure, wherein the valve mechanism comprises, a first adjustmentmember having a valve seal portion and a first thread; a secondadjustment member having a bias member seat and a second thread; a sealmember configured to seal the shunt system when positioned at the valveseal in a seal position; a biasing member configured to bias the sealmember against the valve seal portion with a selected biasing force,wherein the biasing force is selected at least in part by the positionof the first adjustment member relative to the second adjustment member;wherein the first thread of the first adjustment member threadablyengages the second thread of the second adjustment member and to selecta dimension between the seal position and the bias member seat; and aflow limiter assembly having a flow limiter and a cover, wherein theflow limiter is configured to limit a siphon away from the reservoirthrough the valve mechanism.
 18. The shunt system of claim 17, whereinthe biasing member is a coil spring having a selected free length priorto being compressed to a selected compressed length between the biasmember seat and the seal member.